Cytotoxicity and Apoptotic Effects of Microcystin-LR and Anatoxin-a in Mouse Lymphocytes ( microcystin-LR / anatoxin-a / cytotoxicity / mouse lymphocytes / apoptosis )

There is an increasing amount of knowledge on the cytotoxic properties of cyanotoxins, but rela- tively little is known regarding their fine specificity and mechanisms of action. In this study, we investigated the influence of microcystin-LR and AnTx-a on mouse B- and T-lymphocyte subpopulations in vitro. Cyanotox- ins significantly decreased the cell viability after 4 and 24 h, compared to the untreated control. After 24 h exposure to microcystin-LR and anatoxin-a, the viabil- ity of splenocytes dropped to 23% and 57%, respec- tively. Our data demonstrate that microcystin-LR induced apoptosis specifically in mouse B cells, proba- bly via the B-cell antigen receptor and mitochondrial pathway, while the T cells were not affected. AnTx-a showed cytotoxic effects on both lymphocyte subpopu- lations, but the effects were driven by mechanisms dif- ferent from apoptosis. These findings demonstrate that the cyanotoxins could cause cytotoxic alterations in a variety of cell types different from the major targets, operating via distinct mechanisms.